1. Field of the Invention
The present invention relates in general to a color balance monitor, and in particular to a new and useful fiber optic color balance monitor which is capable of measuring color-balance in printing operations.
2. Description of the Related Art
The operator of a color offset printing machine makes adjustments during set-up to provide the proper balance among the different inks required for realistic color rendition. After this initial "timing", the press produces copies at rates of up to twenty (20) copies per second. If the ink delivery changes for any component color during the press run, the resulting color rendition for the prints is degraded and significant amounts of materials and time may be wasted.
There are instruments such as colorimeters that are commercially available which are intended specifically for the measurement of color-balance. For example, U.S. Pat. Nos. 3,885,878; 3,999,860; 4,019,819; 4,150,898; 4,464,054; and 4,909,633 relate to various colorimeters some of which employ fiber optics.
There still exists a desire for a continuous method for monitoring the process during the run so that corrective action can be taken in a timely manner as the color balance deviates from acceptable limits. Several factors place the desired monitoring function beyond the capabilities of the prior art. First, the desired system must have color resolution over a wide area where the color may vary since the prints to be monitored are generally a very complex two-dimensional pattern, a part of which may be in color and the other part in black and white. Second, the system needs to be flexible and convenient to initialize since patterns are different with each press run. Finally, the desired system needs to be very fast since prints pass at rates of up to 20 copies per second.